1. Field of the Invention
The present invention relates to a damper with a vehicle height adjustment function for incorporation in a suspension of vehicles such as automobiles.
2. Description of the Related Art
A damper for vehicles includes a damper main body and a damper rod inserted into the damper main body in such a manner as to freely move therein in vertical directions. One of the damper main body and the damper rod is connected to a spring lower member, while the other is connected to a vehicle body, whereby a damping effect is obtained for vibrations of the vehicle body.
Conventionally, known as a damper with a vehicle height adjustment function is a self-pumping type damper in which a pumping unit is interposed between a vehicle body and the damper for sending oil from a low pressure chamber to a high pressure chamber through pumping actions resulting from vibrations of the vehicle body to thereby raise the vehicle body higher by virtue of the pressure in the high pressure chamber.
The self-pumping type damper has a drawback that the construction of the pumping unit becomes complicated, resulting in high costs. In addition, it has also a drawback that although it is desirable to lower the height of the vehicle when running at high speed for the sake of vehicle running stability, the self-pumping type damper is designed to react only to vibrations and is not adapted to react to the vehicle speed, and therefore with the self-pumping type damper, it is not possible to lower the vehicle height while running at high speed.